Can you compare Zogby polls?

A podcast interview with John Zogby about the Houston Chronicle/KHOU poll.

Some of our readers have asked how the results could be so different between Internet interactive polls produced for The Wall Street Journal by Zogby Interactive and a telephone survey conducted for the Houston Chronicle/KHOU-TV by Zogby International.

One major difference in the two polls is the one done for the Chronicle and KHOU used traditional polling methods: live people calling live people. The Zogby Interactive poll uses a new polling method that Zogby vigorously defends as accurate.

But are they producing the same results, or are the two polling methods apples and oranges?

“It’s two different methodologies, and it is comparing apples and oranges,” Zogby said. “The interactive polling tends to get a much more partisan. The Democrats are real Democrats, and the Republicans are real Republicans.”

Zogby said, “You saw Chris Bell doing better in the interactive poll among hyper-partisan Democrats than he did in the telephone survey.”

The apples to oranges effect can be seen in Strayhorn’s numbers.

Strayhorn jumped eight percentage points between a WSJ poll completed on Oct. 16 and the Chronicle/KHOU poll completed on Oct. 25. But that was followed by another WSJ poll completed Oct 27 showing Strayhorn dropped six percentage points. The swing is out of the margin of error of either poll.

Similarly, Democratic U.S. Senate candidate Barbara Ann Radnofsky jumped almost 10 percentage points from the Zogby poll done for the Chronicle/KHOU and the one released Monday by the WSJ. The latest Zogby Interactive poll also was an increase in support for Radnofsky of eight percentage points over the previous interactive poll.

Absent any major events in the campaigns, such wild swings of support for Strayhorn and Radnofsky fall outside what observers normally expect out of political polling.

A Sept. 5 Zogby Interactive poll had the Senate race with Republican incumbent Kay Bailey Hutchison at 48 percent and Radnofsky at 39 percent. No other poll ever showed the race that close. In fact, a Rasmussen Reports automated telephone survey completed six days before had the race at 58-32, favoring Hutchison.

Now, here are the most recent numbers. The new Zogby Wall Street Journal poll, available the day after your Zogby numbers, had yet another wildly different set of numbers for Sen. Hutchison and me: 55-36.

We agree: the poll that counts occurs Nov 7 and I encourage every eligible voter to go to the polls.

Zogby said the two polls simply have to be viewed separately and cannot be compared. But Zogby said he believes the interactive polling may come closer to reflecting the outcome of an election because it is a survey of the most motivated voters.